What is the equivalent of | % in C# for the below code

Can someone help in translating the below code to C#. I am mainly confused on what should $var |% be in c#?

  $var = dataset.Tables[0]
  $index = 0
  
  $var | %{
   $id=dataset.Tables[0].rows[$index].pid
   .....
   .....
   .....
   $index++
   }